The invention relates to a new electrolytic cell of the diaphragm type. More particularly, it concerns a diaphragm-type cell with vertical anodes rigidly connected to an electrically non-conductive base, for electrolyzing aqueous solutions of alkali chlorides.
In order to obtain improved current distribution it has long been proposed to make use of a current intake to one electrode, in an electrolytic cell, with a uniform current density, e.g., as in U.S. Pat. No. 1,368,206 or U.S. Pat. No. 1,555,424. A current distributor of this type is rectangular in shape.
It has also been proposed, in U.S. Pat. No. 3,432,422, that the anodes should be fixed vertically in a lead matrix; that the intake and distribution of the current should be provided for by bus bars made of copper, each bar being axially centered relative to a bed of anodes; and that the bar should be triangular in shape in order to give uniform current density.
However, it is well known that an electrolytic cell must fulfill several types of requirements. Firstly, the liquor to be electrolyzed is particularly corrosive in the case of aqueous solutions of alkali chlorides, such as sodium chloride. In addition, the anodes must be mounted in a particularly impervious manner.
Furthermore, more and more metal anodes are being used in electrolytic cells, since these have the advantage of having great dimensional stability with the passage of time. This advantage allows for maximum reduction of the inter-polar distance between anode and cathode but consequently entails mechanically very rigid mounting of the anodes.
For reasons of upkeep and maintenance, it is also necessary to have the fixing means easily accessible, so that the anodes may readily be replaced.
It has, therefore, already been proposed, in French Pat. No. 1,600,249 and its patent of addition (No. 2,164,495), to use vertical, plane and hollow anodes which, in the case of at least one of their two parallel faces, are formed by a perforated sheet or a grating made from titanium, a similar metal or an alloy of such metals; the anodes are fixed on the base of the cell of extensions which pass through the base; the extensions comprise a core made of a highly conductive metal and covered with a sheath of titanium, a similar metal or an alloy of such metals, and good electrical contact is provided between the sheath and the core.
However, although this proposal provides for good passage of current into the electrode itself and for good positioning of the electrode, it provides no remedy for the other drawbacks mentioned above.
The present invention aims to provide a new arrangement of the cell components which, apart from good current distribution with minimum leakage, will provide for an anode assembly which is stable and reliable with the passage of time, readily accessible and of excellent imperviousness.
It is, accordingly, an object of the present invention to provide an electrolytic cell of the diaphragm type which overcomes the drawbacks of the prior art.
It is also an object of the present invention to provide an electrolytic cell having an anode assembly which is stable, reliable, readily accessible and of superior imperviousness to corrosion.